Re: [patch V2 0/7] fs: Substitute bit-spinlocks for PREEMPT_RT and debugging

[Thomas Gleixner]

Christoph,

On Fri, 2 Aug 2019, Christoph Hellwig wrote:

> did you look into killing bÑt spinlocks as a public API instead?

Last time I did, there was resistance :)

But I'm happy to try again.

> The main users seems to be buffer heads, which are so bloated that
> an extra spinlock doesn't really matter anyway.
>
> The list_bl and rhashtable uses kinda make sense to be, but they are
> pretty nicely abstracted away anyway.  The remaining users look
> pretty questionable to start with.

What about the page lock?

  mm/slub.c:      bit_spin_lock(PG_locked, &page->flags);

Thanks,

	tglx